Tris(N-carbalkoxylaminomethyl)phosphine oxides and sulfides

ABSTRACT

The title compounds, having the formula (RO2CNHCH2)3PY where Y=oxygen or sulfur, are prepared by reacting a tris(N-carbalkoxylaminomethyl)phosphine, having the formula (RO2CNHCH2)3P, with an oxidizing or sulfurizing agent. The products, after methylolation with formaldehyde, are useful as finishing agents for imparting flame retardant properties to cotton fabrics.

This is a division of application Ser. No. 964,852 filed Nov. 29, 1978,now U.S. Pat. No. 4,249,017.

CROSS REFERENCE TO RELATED APPLICATIONS

U.S. Pat. No. 4,204,072--"TRIS(N-CARBALKOXYLAMINOMETHYL)PHOSPHINES"

U.S. Pat. No. 4,171,448--"QUATERNARY PHOSPHONIUM SALTS BEARING CARBAMATEGROUPS"

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to novel tris(N-carbalkoxylaminomethyl)phosphineoxides and sulfides and to methods for preparing the same.

(2) Description of the Prior Art

Nowhere in the prior art do there exist tertiary phosphine oxides andsulfides containing carbamate groups attached to each of the phosphorussubstituents through its nitrogen atom.

Furthermore, the preparation and properties of such compounds, togetherwith methods for their methylolation, and their application to cottonfabrics for the purpose of imparting flame retardant properties to thecotton, has not been known previously.

SUMMARY AND OBJECTS OF THE INVENTION

The instant invention discloses as new compoundstris(N-carbalkoxylaminomethyl)phosphine oxides and sulfides having theformula (RO₂ CNHCH₂)₃ PY, where R is an alkyl radical having from 1 to 6carbon atoms and Y is selected from the group of oxygen and sulfur, andthe processes for producing said compounds.

It is the principal object of this invention to prepare noveltris(N-carbalkoxylaminomethyl)phosphine oxides and sulfides by methodswhich prevent interaction of products and by-products.

It is another object of the invention to prepare derivatives oftris(N-carbalkoxylaminomethyl)phosphine oxides and sulfides that areuseful as finishing agents for cotton textile fabrics, giving fabricswith improved flame resistance properties.

Other objects and improvements of this invention will become obviousfrom the description of the preferred embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The novel compounds of this invention have the general formula (RO₂CNHCH₂)₃ PY, where R is an alkyl or substituted alkyl radical havingfrom 1 to 6 carbon atoms, and Y is selected from the group of oxygen andsulfur.

In accordance with the practice of this invention, the new compounds areprepared by reacting a tris(N-carbalkoxylaminomethyl)phosphine havingthe formula (RO₂ CNHCH₂)₃ P, where R is as defined above, with anoxidizing or sulfurizing agent, and recovering the product from theresulting reaction mixture.

The tris(N-carbalkoxylaminomethyl)phosphines, themselves novelsubstances, are prepared as described in my co-pending application U.S.Pat. No. 4,204,072, TRIS(N-CARBALKOXYLAMINOMETHYL)PHOSPHINES. Examplesof such substances are tertiary phosphines in which R is methyl, ethyl,isopropyl, 2-methoxyethyl, n-butyl, and the like.

The oxidizing agents employed in the practice of this invention comprisegases such as air, oxygen, oxides of nitrogen including nitric oxide anddinitrogen tetroxide, sulfur dioxide, and the like, inorganic substancessuch as hydrogen peroxide, mercuric oxide, potassium permanganate,chromic acid, and the like, and organic substances such as alkylhydroperoxides, peroxy acids, diacyl peroxides, epoxides, ozonides, andthe like.

The sulfurizing agents employed in the practice of this inventioncomprise elemental sulfur, inorganic substances such as sodiumpolysulfide, ammonium sulfide, mercuric sulfide, thiophosphorylchloride, thiocyanogen, and the like, and organic substances such asmercaptans, episulfides, thionocarbonates, dialkyl disulfides, and thelike.

The reaction between the tris(N-carbalkoxylaminomethyl)phosphine and theoxidizing or sufurizing agent is most conveniently carried out in thepresence of a solvent such as water, ethanol or acetone, but may also beperformed in the absence of a solvent. The molar ratio may be variedfrom 10:1 to 1:10, the preferred ratio being 1:1. The temperature may bevaried from 0° C. to 100° C., depending on the strength of the oxidizingor sulfurizing agent and the physical properties of the solvent. Thepressure may be atmospheric, subatmospheric or higher than atmospheric.If the tertiary phosphine is air-sensitive, as is often the case, thereaction may be carried out in an atmosphere of an inert gas such asnitrogen or argon.

If the base used in the preparation of thetris(N-carbalkoxylaminomethyl)phosphine is a preferred base of the typedisclosed in my co-pending application U.S. Pat. No. 4,204,072,TRIS(N-CARBALKOXYLAMINOMETHYL)PHOSPHINES, i.e. a base capable oftrapping the by-product formaldehyde or formaldehyde derivative, thetertiary phosphine need not be isolated and purified. In such a case,the oxidizing or sulfurizing agent can be added directly to the reactionmixture containing the base and the tertiary phosphine. The consequenceis a considerable saving of time and effort. Illustrations of thistechnique are given in Examples 4, 5 and 6.

If the base used in the preparation of thetris(N-carbalkoxylaminomethyl)phosphine is not a preferred base, asdefined in the preceding paragraph, the subsequent oxidation orsulfurization yields a product distinctly different from that obtainedthrough the use of a preferred base. This is illustrated in Example 7,where the base is sodium hydroxide. The product of Example 7 is acolorless oil, whereas that of Example 4, employing the same quaternaryphosphonium salt, is a high-melting crystalline solid. Their spectra,solubility and other physical properties are also different. Efforts tointerconvert the products by reaction of the crystalline product withmethyl N-hydroxymethylcarbamate in the presence or absence of sodiumhydroxide catalyst, or by treatment of the liquid product with ammoniumhydroxide, were not successful.

Melting points are corrected. Elemental analyses were performed bycommercial laboratories. IR spectra were taken on a Perkin-Elmer 137Bwith NaCl optics (w=weak, m=medium, s=strong, vs=very strong). ¹ H NMRspectra were taken on a Varian HA-60-IL at 24.3 MHz, using 85% H₃ PO₄ asan external reference (s=singlet, d=doublet, t=triplet, m=multiplet).Chemical shifts downfield of the reference are positive in both cases.

EXAMPLE 1

This example illustrates the preparation oftris(N-carbomethoxylaminomethyl)phosphine oxide, (CH₃ O₂ NHCH₂)₃ PO,hereinafter referred to as TMPO, fromtris(N-carbomethoxylaminomethyl)phosphine, (CH₃ O₂ CNHCH₂)₃ P,hereinafter referred to as TMP.

A 30% solution of hydrogen peroxide (57.0 g, 0.5 mol) was added dropwiseto a vigorously stirred slurry of 147.6 g (0.5 mol) of TMP in 500 ml ofacetone under an argon atmosphere. Ice-bath cooling was applied asnecessary to counter the strongly exothermic reaction. The TMP graduallydissolved, and was all in solution when two-thirds of the peroxide hadbeen added. About 10 min. after the addition was completed, the productstarted to crystallize. Next day, the solid was collected on a filter,washed with acetone and dried, giving 98.9 g (63.5% yield) of TMPO, mp179°-180° C. Work-up of the filtrate raised the yield to 126.0 g (81.0%yield). Two recrystallizations from ethanol afforded pure TMPO as awhite, crystalline solid, mp 189°-190° C. IR (Nujol): 780m, 830w, 852m,972w, 1015m, 1135m, 1145m, 1160m, 1190m, 1260s, 1300m, 1540s (NH, amideII), 1710vs br (C═O, amide I), 3250w (NH, bonded) and 3400w (NH, free)cm⁻¹. ¹ H NMR (DMSO-d₆): δ3.60 (s, CH₃), 3.47 (t, CH₂, J=9.0 Hz,blending into the CH₃ peak with D₂ O; combined CH₃ and CH₂, 15H), and7.34 (m, 3H, NH, vanishing with D₂ O) ppm.

Anal. Calcd for C₉ H₁₈ N₃ O₇ P: C, 34.73; H, 5.83; N, 13.50; P, 9.95.Found: C, 34.69; H, 5.70; N, 13.48; P, 10.00.

The phosphine oxide TMPO is soluble in chloroform and insoluble inwater, acetone, and the common organic solvents. It can berecrystallized from ethanol (25 ml/g) or water. When heated above itsmelting point, it gases without discoloration and froths to atan-colored resin at 260° C.

EXAMPLE 2

Hydrogen peroxide (30%) was added dropwise to a well-stirred slurry of1476.2 g (5 mols) of TMP in 2000 ml of water under an argon atmosphere,with ice-bath cooling applied as needed to maintain the reactiontemperature between 20° and 30° C. The addition was stopped after 3.5hr, when 550.6 g (4.85 mols) of 30% hydrogen peroxide had been added. Atthis point, an iodine test for unreacted TMP was negative, and theproduct, which had separated during the reaction, abruptly foamed to thesurface. The product was collected on a filter, rinsed with water andair-dried, giving 826.6 g (53.1% yield) of crystalline TMPO, mp179°-180° C.

EXAMPLE 3

This example illustrates the preparation oftris(N-carbomethoxylaminomethyl)phosphine sulfide, (CH₃ O₂ CNHCH₂)₃ PS,hereinafter referred to as TMPS, from TMP.

A mixture of 2.95 g (0.01 mol) of TMP, 0.32 g (0.01 g-atom) of sulfurand 25 ml of benzene was heated to reflux under an argon atmosphere.After 1 hr, most of the solids had dissolved. The mixture was cooled andstripped of benzene under reduced pressure. The residue was taken up inhot acetone, filtered hot to remove the unreacted sulfur (0.12 g), andstripped again under reduced pressure, leaving 2.40 g (73.4% yield) ofTMPS as a white, crystalline solid. Two recrystallizations from ethanolafforded pure TMPS, mp 136.5°-137° C. IR (Nujol): 772w, 780w, 790w,810w, 846m sh, 855s, 970m, 1015s br, 1145s, 1190s, 1240vs, 1290vs,1520vs br (NH, amide II), 1710vs and 1740s (C═O, amide I), and 3400s(NH) cm⁻¹. ¹ H NMR (DMSO-d₆): δ3.61 (s, CH₃), 3.72 (t, CH₂, J=3.0 Hz,collapsing with D₂ O to d, J=3.0 Hz; combined CH₃ and CH₂, 15H), and7.39 (m, 3H, NH, vanishing with D₂ O] ppm. ³¹ P NMR (DMSO): δ48.5 ppm.

Anal. Calcd. for C₉ H₁₈ N₃ O₆ PS: C, 33.03, H, 5.54; N, 12.84; P, 9.46;S, 9.80. Found: C, 33.08; H, 5.49; N, 12.82; P, 9.60; S, 9.80.

The phosphine sulfide TMPS is soluble in chloroform, and insoluble inwater or ethanol. It can be recrystallized from ethanol (6 ml/g),2-propanol or water.

EXAMPLE 4

This example and the two which follow illustrate the use of a preferredbase, ammonium hydroxide, in the preparation of TMPO or TMPS fromtetrakis-(N-carbomethoxylaminomethyl)phosphonium chloride, (CH₃ O₂CHNCH₂)₄ PCl (TMPC), or octakis(N-carbomethoxylaminomethyl)diphosphoniumsulfate, [(CH₃ O₂ CNHCH₂)-₄ P]₂ SO₄ (OMPSf).

Conc. ammonium hydroxide (10 ml) was added to a well-stirred slurry of20.94 g (0.05 mol) of TMPC in 100 ml of water in an apparatus previouslypurged with argon. The mixture gradually thickened. After 2 hr. themixture, still containing the excess base and the by-products, wastreated dropwise with 5.67 g (0.05 mol) of 30% hydrogen peroxide over a20 min. period, with ice-bath cooling applied as needed to keep thetemperature below 30° C. Next day, the mixture was stripped to drynessin a rotary evaporator, triturated with ethanol and filtered, giving13.69 g (88.0% yield) of crystalline TMPO, mp 176°-178° C.

TMPC is not oxidized by hydrogen peroxide in the absence of a base.

EXAMPLE 5

An identical experiment in which the excess base and by-products wereremoved prior to oxidation gave 13.91 g (89.4% yield) of crystallineTMPO, mp 174°-177° C.

EXAMPLE 6

Conc. ammonium hydroxide (500 ml) was added to a solution of 1078.4 g(1.25 mol) of OMPSf in 1500 ml of water in an apparatus previouslypurged with argon. TMP started to separate within minutes. After 2 hr.the mixture, still containing the excess base and the by-products, wastreated dropwise with 977 g (2.87 mol) of 20% ammonium sulfide over a 2hr. period at 25°-30° C. Next day, the product was collected on afilter, rinsed thoroughly with water and air-dried, giving 521.4 g ofcrude TMPS, mp 120°-125° C. One recrystallization from ethanol gave398.3 g (48.9% yield) of crystalline TMPS, mp 132°-135° C.

EXAMPLE 7

This example illustrates the effect of using a base--sodium hydroxide,which is not one of the preferred bases--on the preparation of TMPO fromTMPC.

A slurry of 20.94 g (0.05 mol) of TMPC in 50 ml of water was treateddropwise with a solution of 2.00 g (0.05 mol) of sodium hydroxide in 25ml of water. During the addition, which took 5 min, the mixture cleared,turned milky, and cleared again. After 15 min, the solution wasextracted with chloroform, and the chloroform extract filtered andstripped. The residue (16.79 g), a viscous, colorless oil which, unlikeTMP, could not be induced to crystallize, was dissolved in 100 ml ofacetone and treated dropwise with 5.70 g (0.05 mol) of 30% hydrogenperoxide over a 5 min period. The temperature rose to 40° C., and at theend an iodine test for unreacted tertiary phosphine was negative. Thesolution was stripped of acetone in a rotary evaporator, taken up inchloroform, extracted with water to remove any remaining peroxide,filtered, and stripped again, giving 14.00 g (62% yield) of the tertiaryphosphine oxide as a colorless oil, n_(D) ²⁰ 1.4962. IR (neat): 775w,1005w br, 1055w, 1150m, 1190m, 1250s, 1290m sh, 1530s (NH, amide II),1710vs (C═O, amide I), and 3350m (NH) cm⁻¹. ¹ H NMR (CDCl₃): δ3.7-3.9(m, 12H, CH₃), 3.9-4.6 (m, 8H, PCH₂), 6.63 (m, 2H, NH), and 8.13 (m, 1H,NH) ppm. ³¹ P NMR (CHCl₃): δ45.3 ppm. The elemental analyses (N, 10.82;P, 5.98) clearly showed a 4:1 molar ratio of nitrogen to phosphorus, asopposed to 3:1 in TMPO.

The product was soluble in water, ethanol, acetone and chloroform, andinsoluble in ether, carbon tetrachloride, ethyl acetate and benzene.

METHYLOLATION OF THE PRODUCTS

The novel tris(N-carbalkoxylaminomethyl)phosphine oxides and sulfides ofthis invention each contain three NH groups which are available forreaction with crosslinking agents such as formaldehyde, glyoxal, and thelike. The reaction of TMPO with formaldehyde is illustrated by thefollowing equation: ##STR1##

TMPO is insoluble in 37% formalin solution, but in the presence of anacid or base catalyst the TMPO dissolves, giving a mixture of N-methylolderivatives in which the trimethylol derivative is predominant. If thecatalyst is a base, such as sodium hydroxide or disodium phosphate, thereaction may be carried out at room temperature (about 25° C.), withwarming to 60° to 80° C. if desired; no TMPO separates when the solutionis neutralized, even if no warming has been applied. If the catalyst isan acid, such as hydrochloric acid, the reaction mixture must be heatedbriefly to about 75° C., whereupon the TMPO dissolves, giving the samemixture of products as the base-catalyzed reaction. There is no evidenceof crosslinking, i.e. formation of N--CH₂ --N links between carbamateresidues, of the kind encountered in the acid-catalyzed condensation offormaldehyde with unsubstituted carbamates (J. F. Walker,"Formaldehyde", Reinhold Publishing Corp., New York, 3rd ed., p. 391).

The N-methylol derivatives, though stable in aqueous solution, are notstable in alcohol solution. Dissociation occurs within a few hours inethanol or a few minutes in methanol, regenerating crystalline TMPO.This precludes the use of alcohols as solvents for the methylolation ofTMPO, and explains why efforts to prepare methoxymethyl derivatives ofTMPO by reaction with paraformaldehyde in methanol were unsuccessful.Competition for formaldehyde evidently favors the alcohol (hemiacetalformation) in alcohol solutions and TMPO (methylolation) in aqueoussolution, and suggests that, as a nucleophile, TMPO is stronger thanwater but weaker than alcohols.

It may be noted in passing that a similar dissociation occurs whenattempts are made to recrystallize methyl N-methylolcarbamate, CH₃ O₂CNHCH₂ OH, from alcohols such as 2-propanol or t-butanol.

Attempts to measure the extent of methylolation of TMPO by the sulfitemethod (Walker, op. cit., p. 486) were unsuccessful. Cleavage offormaldehyde from the methylolated TMPO occurred even under the leastfavorable conditions, i.e. in ice-cold acid, using the proceduredescribed by J. D. Reid, R. M. Reinhardt and J. S. Bruno, Amer. DyestuffRep., 54, P 485-91 (1965).

Methylolated TMPO does not appear to react with gaseous ammonia,ammonium hydroxide or dimethylamine, but does react with urea ordimethylolurea giving insoluble, polymeric products.

EXAMPLE 8

A slurry of 6.22 g (0.02 mol) of TMPO and 8.11 g (0.10 mol) of 37%formalin in 25 ml of water was treated with 10 drops of 0.1 N sodiumhydroxide, stirred until the TMPO dissolved, and then heated for 10 minat 80° C. to complete the reaction. After cooling, the solution wasstripped on a rotary evaporator and dried under vacuum, giving 8.27 g(103.1% yield) of colorless oil, n_(D) ²⁰ 1.5008. IR (neat): 774m, 875m,970w, 1015s, 1040s, 1110m, 1160s br, 1250s, 1280s, 1540m, (NH, amideII), 1710 vs (C═O), amide I), and 3400s (OH) cm⁻¹. The NH absorption wasgreatly diminished, relative to C═O. ¹ H NMR (DMSO-d₆): δ3.66 (s, CH₃),3.9 (m, PCH₂), 4.7 (m, OCH₂), and 5.9 (t, OH), together with a littleunreacted formaldehyde and TMPO.

EXAMPLE 9

TMPO (6.22 g, 0.02 mol) was added in portions to 4.87 g (0.06 mol) of37% formalin solution buffered to pH 8 with 0.20 g of disodium phosphatedodecahydrate and 2 drops of 0.1 N sodium hydroxide. After the addition,the solution was heated briefly to boiling to complete the reaction,cooled, stripped on a rotary evaporator and dried under vacuum, giving7.69 g (95.9% yield) of methylolated TMPO, identical (IR) to the productof Example 8.

EXAMPLE 10

A slurry of 6.22 g (0.02 mol) of TMPO and 4.87 g (0.06 mol) of 37%formalin in 10 ml of water was treated with 5 drops of conc.hydrochloric acid, stirred 1.5 hr. and then heated briefly to 75° C.,whereupon the TMPO dissolved. After cooling, the solution was strippedon a rotary evaporator and dried under vacuum, giving 8.07 g (100.6%yield) of colorless oil, n_(D) ²⁰ 1.4980, identical (IR,NMR) to theproduct of Example 8.

EXAMPLE 11

A solution of 8.22 g (0.02 mol) of the product of Example 7 and 8.11 g(0.10 mol) of 37% formalin in 25 ml of water was made alkaline to pH 9with 10% sodium hydroxide, allowed to stand overnight, stripped on arotary evaporator and dried under vacuum, giving 9.25 g (94.7% yield) ofcolorless oil. IR (neat): 772m, 1020s, 1110m, 1170s, 1190s, 1250s, 1535m(NH, amide II), 1700vs (C═O, amide I), and 3400s (OH) cm⁻¹. The NHabsorption was greatly diminished relative to C═O.

APPLICATION OF THE PRODUCTS TO COTTON

Carbamates are employed extensively in the textile industry to impartdurable press properties to cotton fabrics (H. F. Mark, N. S. Woodingand S. M. Atlas, "Chemical Aftertreatment of Textiles",Wiley-Interscience, New York, 1971, pp. 417-64). Some attempts have beenmade to incorporate phosphorus in these finishes to also impart flameretardant properties to the cotton fabrics, without notable success (W.A. Reeves and R. M. Perkins, Colourage Annual 1 [1971]).

In a companion application, U.S. Pat. No. 4,171,448, QUATERNARYPHOSPHONIUM SALTS BEARING CARBAMATE GROUPS, I have shown how to preparenovel quaternary phosphonium salts bearing one or more carbamate groupsattached through nitrogen, and have demonstrated the usefulness of thesephosphonium salts as finishing agents for cotton. In the paragraphs thatfollow, I shall disclose the techniques that may be applied to the novelcompounds of this invention to render them useful as finishing agentsfor cotton.

The novel tris(N-carbalkoxylaminomethyl)phosphine oxides and sulfides ofthis invention each contain nitrogen and phosphorus, the two elementsthat are considered necessary and sufficient for imparting flameretardant properties to cotton fabric. The elements, moreover, are inthe ratio of 3 parts nitrogen to 1 part phosphorus that is considered tobe optimum for flame retardant efficiency, and the phosphorus is in aform that needs no further stabilization.

For practical purposes, it is also desirable that the flame retardantfinish be durable to laundering. To this end, methods are given forchemically binding the novel compounds to the cotton cellulose throughthe use of cross-linking agents such as formaldehyde. Examples 12 to 17illustrate the application of TMPO to cotton printcloth, withformaldehyde as the binding agent. The TMPO is first methylolated, asdisclosed in the preceding section, and is then caused to react with thecotton cellulose by curing at an elevated temperature in the presence ofa catalyst. The catalyst, it may be noted, can be either an acid or abase. Example 18 illustrates the application of this finish to cottonsateen. Examples 19 to 23 illustrate the application of TMPO to cottonprintcloth with urea, melamine or their methylol derivatives asco-reactants.

The flammability of the treated fabric was determined by the OxygenIndex (O.I.) Test, as described in the "Annual Book of ASTM Standards",American Society for Testing and Materials, Philadelphia, 1974, Part 35,p. 732, or by the Match Test, as described by W. A. Reeves and G. L.Drake, Jr., "Flame Resistant Cotton", Merrow, Watford Herts., England,1971, p. 14. Wrinkle recovery (WRA, W+F, conditioned) was determined bythe Monsanto test, as described in the "Annual Book of ASTM Standards",op. cit., Part 32, p. 226.

Phosphorus analyses were performed by the X-ray fluorescence method,nitrogen analyses by the Kjeldahl method, and formaldehyde analyses bythe chromatropic acid method after digestion with sulfuric acid.

EXAMPLES 12 TO 17

These examples illustrate the application of TMPO to cotton fabric withformaldehyde as the binding agent.

In each case, the padding formulation was prepared by dissolving 13.07 g(42 mmol) of TMPO in a solution of 0.20 g of sodium hydroxide in 10.23 g(126 mmol) of 37% formalin, neutralizing to pH 7 with 6 N HCl, adding12.5 mmol of the catalyst and 0.1 g of Triton X-100 (a wetting agent),and making up to 50 g with water. The final pH of each formulation isgiven in the table.

An 80×80 desized, scoured and bleached cotton printcloth was cut into6"×12" swatches, immersed in one of the formulations, padded to about a95% wet pickup, dried at 85° C. for 4 min in a forced draft oven, andcured at 160° C. for 4 min in another forced-draft oven. The swatcheswere then rinsed for 15 min in hot running tap water and line dried. Theresults for a series of such experiments with various catalysts areassembled in Table I.

The add-on was negligible in the absence of a catalyst (Example 15), butincreased to 5 to 10% when either an acid or a base catalyst was addedto the formulation. Sodium carbonate (Example 16) and magnesiumchloride/citric acid (Example 12) gave comparable add-ons, provided thatthe cure time for the former was extended to 10 min. Magnesiumchloride/citric acid (Example 12) gave comparable add-ons, provided thatthe cure time for the former was extended to 10 min. Magnesium chlorideby itself (Example 14) was not sufficiently acidic to be an effectivecatalyst. The flame resistance (O.I.) and wrinkle resistance (WRA) bothincreased with add-on when the catalyst was an acid, but only the flameresistance increased when the catalyst was a base.

EXAMPLE 18

Application of the methylolated TMPO formulation to cotton sateen withmagnesium chloride/citric acid catalyst, as described in Example 12,gave fabric with an 11.6% add-on and a 90° match test angle. Theseresults were similar to those obtained with the printcloth.

EXAMPLES 19 TO 23

These examples illustrate the application of TMPO to cotton fabric withurea or melamine as co-reactants, and formaldehyde as the binding agent.

In each case, the padding formulation (50 g) contained 13.07 g (42 mmol)of TMPO, 84 mmol of the co-reactant, 12.5 mmol of catalyst and 0.1 g ofTriton X-100. In all but Example 20, the TMPO was methylolated with10.23 g (126 mmol) of 37% formalin prior to addition of the co-reactant.In Examples 20 and 21, 10.07 g (84 mmol) of crystallineN,N'-dimethylolurea was substituted for the urea, and in Example 23 5.30g (42 mmol) of melamine was substituted for the urea. The compositionand final pH of each formulation are given in Table II.

With magnesium chloride as the catalyst, melamine helped to bind themethylolated TMPO to the fabric (Example 23), but urea did not (Example22). Sodium dihydrogen phosphate, a mildly acidic catalyst, was tooacidic for use with melamine, but helped urea to bind the methylolatedTMPO to the fabric, especially when both the urea and the TMPO weremethylolated prior to padding (Example 21). The fabrics with the highestadd-on passed the match test with an angle of 110°.

The foregoing examples are given to illustrate the preparation andproperties of the novel compounds of this invention, and their use asflame retardants for cotton. The examples are given merely for purposesof illustration, and should not be construed as limiting the scope ofthe invention.

                                      TABLE 1                                     __________________________________________________________________________    Example                                                                            Catalyst pH % Add-on                                                                            % P                                                                              % N                                                                              % CH.sub.2 O                                                                       O.I.                                                                              WRA                                     __________________________________________________________________________    12   MgCl.sub.2 /citric acid                                                                2.3                                                                              10.0  1.07                                                                             1.16                                                                             2.76 0.211.sup.a                                                                       280                                     13   Zn(NO.sub.3).sub.2                                                                     5.5                                                                              8.4   0.86                                                                             0.92                                                                             1.34 0.210.sup.a                                                                       252                                     14   MgCl.sub.2                                                                             6.5                                                                              1.5   0.08                                                                             0.13                                                                             0.09 0.183                                                                             207                                     15   None     7.0                                                                              1.0   0  0.01                                                                             0.17 0.179                                                                             194                                     16   Na.sub.2 CO.sub.3                                                                      10.7                                                                             6.1   0.73                                                                             0.73                                                                             0.06 0.214                                                                             192                                     "    Na.sub.2 CO.sub.3.sup.b                                                                "  9.0   1.05                                                                             1.21    0.234                                                                             212                                     17   NaOH     11.8                                                                             4.3   0.62                                                                             0.62                                                                             0.01 0.204                                                                             192                                     __________________________________________________________________________     .sup.a Match test angle 80°.                                           .sup.b Cured 10 min at 160                                               

                  TABLE II                                                        ______________________________________                                        Ex-                           %                                               am-            TMPO    Urea   Add-         Match                              ple  Catalyst  methylolated                                                                             pH  on   % P  % N  angle                            ______________________________________                                        19   NaH.sub.2 PO.sub.4                                                                      Yes     No   4.7 12.2 0.32 3.05 20                             20   MgCl.sub.2                                                                              No      Yes  5.6 11.3 0.24 2.72 20                             21   NaH.sub.2 PO.sub.4                                                                      Yes     Yes  4.9 35.0 1.50 4.68 110                            22   MgCl.sub.2                                                                              Yes     No   6.6  5.8 0.17 1.04  0                             23   MgCl.sub.2                                                                              Yes     No.sup.a                                                                           6.7 34.4 0.92 7.75 80                             ______________________________________                                         .sup.a Melamine                                                          

What is claimed is:
 1. A process for methylolating a tris(N-carbalkoxylaminomethyl)phosphine oxide which comprises reacting the substance with three or more molar equivalents of formaldehyde in aqueous solution in the presence of an acid catalyst; and recovering the product from the resulting reaction mixture.
 2. The process of claim 1, wherein the catalyst is hydrogen chloride. 